1. Field of the Invention
The present invention relates in general to automatic transmission shift control devices for vehicles and more particularly to a sealing structure for an automatic transmission shift control device.
2. Description of the Prior Art
An automatic transmission shift control device includes a shift lever manually operated to control shift of gears of the transmission. The shift lever is pivotally supported by a box-shaped support member fixed to a vehicle floor, so as to be swingable or rotatable forward and rearward of the vehicle. A control lever is provided to extend away from a pivot portion of the shift lever and penetrates through the vehicle floor to protrude outward of the vehicle body. A connecting link is provided between the control lever and the transmission.
An opening is thus formed in the vehicle floor for allowing turn or rotation of the control lever to prevent ingress of rain, mud, etc., on a road surface into the inside of the vehicle body through the opening, a boot is sealingly placed around the control lever and has a peripheral portion fixedly attached to a vehicle floor portion around the opening to sealingly close the opening.
As shown in FIG. 3, a control lever 1 extends downward through an opening 3a of a vehicle floor 3 and projects outward therefrom. A boot 2 has a seal portion 2a sealingly placed around the control lever 1 and a peripheral portion pushed against the vehicle floor 3 by means of a pan or base plate section 5 of a support member 4. The peripheral portion of the boot 2 is formed with a looped seal projection 6 brought into sealing contact with the vehicle floor 3. The opening 3 of the vehicle floor 3 is thus sealingly closed by the boot 2.
Recently, it has been proposed to form the above described support member 4 out of a resinous material and into one piece. That is, as shown in FIG. 4, a support member 4a has an integral base section 5a formed out of a resinous material into one piece and is adapted to be fixed directly to the vehicle floor 3. In this instance, the height "h" of the base portion 5a equivalent to the above described pan 5 needs to be of a predetermined size in order to retain the strength, and further the width "W1" also needs to be of a predetermined size in order that the base portion 5a can push down the projection 6 in a desired manner. However, the width "W1" is desired to be as small as possible, preferably 2 to 3 mm, since a large thickness variation is not desirable for such a support member 4a molded out of a resinous material into one piece.
Thus, as shown in FIGS. 5 and 6, it has been proposed a sealing structure having a rib projection 4b formed of a resinous material and integral with the base portion 5a of the support member 4a, which portion is fitted in a groove 2b of a rectangular cross section, formed in the peripheral portion of the boot 2a, as described in Japanese Utility Model Provisional Publication No. 59390.
However, since the sealing structure of the above publication is such that the width "W2" of the rib projection 4b adapted to push the seal projection 6 against the vehicle floor 3 is small, a sufficient sealing effect cannot be attained unless the fitting relation between the groove 2b and the projection 4b is severely controlled. Accordingly, the work for fitting the rib projection 4b in the groove 2b becomes very difficult, thus lowering the workability at the time of assembly. When the width of the groove 2b is made wider for making the fitting relation more loose, the rib projection 4b may possibly be moved from a position where it is aligned with the seal projection 6, i.e., from a position where the rib projection 4b and the seal projection 6 are located correspondingly on opposite sides of the boot 2, so that it becomes impossible for the seal projection 6 to be pushed correctly or in a desired manner by the rib projection 4b, thus deteriorating the sealing ability of the structure.
That is, it is important for the sealing structure for providing a seal between the support member made of a resinous molding and the boot. It is important to push the seal projection against the vehicle floor by the face of an object having a proper width since it is impossible to attain a desired sealing ability due to movement of the rib projection relative to the seal projection if the width is improper. Further, it is important for a resinous molding to have a substantially equal thickness (2.about.3 mm) to attain a good workability and a dimensional accuracy.